Thiosulfenyl dithiocarbamates as fungicides



Patented June 3, 1952 THIOSULFENYL DITHIOCARBAMATES AS FUNGICIDES LyleD. 'Goodhue, Bartlesville, )kla., and Winston M. Florence, Manhattan,Kans., assignors to Phillips Petroleum Company, a corporation ofDelaware No Drawing. Application March 24, 1950,

Serial No. 151,814

13 Claims.

This invention relates to new fungicides, namely, thiosulfenyldithiocarbamates, which have been discovered to be useful for thetreatment of plant diseases.

We have now discovered that thiosulfenyl dithiocarbamates are excellentfungicides. The compounds of the present invention may be represented bythe following general formula is a primary or secondary amino group inwhich R and R may be hydrogen, alkyl or aryl groups or radicals whichtogether with the N form a saturated heterocyclic ring such asmorpholine or piperidine, wherein said saturated heterocyclic ringcontains not more than six members, where in R" may be an alkyl or arylgroup and the sum of the R groups shall not exceed thirty carbon atomsand R, R and R" may be alike or different.

In the fungicide art it is well known that cer-' tain so-calledfunctional groups are the reason for which a particular compoundpossesses fungicidal efiicacy. Even a slight variation in the basicstructure or composition of the functional group will often, if notactually always, destroy the fungicidal efficacy of the particularcompound. However, variation in or substitution of the so-callednon-functional or inactive groups or substituents of a fungicidalcompound will not alte'rits nature although it may change the degree ofits emcacy, making it more or less valuable as a fungicidalsubstanceH-In view of the foregoing it is essential to note that everycompound according to this invention mustbe a thiosulfenyldithiocarbamate and must therefore contain the functional group Thecompounds of this invention are effective for the prevention'of fungusdiseases such as.

2, peach brown rot, apple bitter rot, and those caused by other fungifound on trees,-grain, flowers, and other plants. They are valuable asdisinfectants for seeds such as rice-barley, peas and others. They mayalso be used in greenhouses to prevent damping oil? or rotting ofvarious plants above the surface of the ground. They may be used totreat seed potatoes'for the prevention of scab and may be used to treatgladiola bulbs for the prevention of rust. Another application of thesecompounds is for the impregnation of shoes, tents, textiles, leatheritems, etc., for the prevention of various mold formations thereon.

The compounds of this invention may be applied for their intendedpurpose by any suitable method such as by spraying as solutions,suspensions or the like. When used as seed disinfectants they may bemixed with talc or other inert diluent powders and sprinkled or shakenwith the seed. I

The compounds of the present invention are fungicidal in extremely lowconcentrations and provide a complete kill on many fungi inconcentrations as low as one part per million. A fungicide is consideredgood if it' kills fungus spores at'10 parts per million.

The compounds of the present invention may be obtained from any suitablesource. One method for their production comprises reactingalkyl-thiosulfenyl halides with alkali metal salts of dithiocarbamicacids. 7 I

Seven day old cultures of ScZ'erotinia fructicola (each brown rot),Alternaria oleracea (a blight) and Glomerella cingulata (apple bitterrot) were used in the following examples as test organisms. These sporeswere obtained under controlled conditions.

Spores to be used in tests were transferred from cultures containing thesame'by adding one ml. of Czapeks solution 1 and 10 ml. of distilledCzapeks solution is a synthetic liquid medium composed ofinorganic'salts and sugar. It is used as a spore nutrient when the fungiare on the slides. The medium ma? Be solidified by the addition of agar.The formula is as o ows:

, .Grams Magnesium sulfate 0.50 Dipotassium acid phosphate 1.00Potassium chloride 0.50 Sodium nitrate A 2.00 Ferrous sulfate 0.01 Canesugar 30.00

Distilled water to make 1000 cc.

3 water to agar slants and shaking. The resulting suspensions containedenough spores to give 10 to 20 spores per low power field (18X ocular,16 mm. (10X) objective).

Example I The spore germination method of evaluating fungicides was usedto determine the activity of '15 scope slide and allowed to spread to acircleabout 5 mm. area. The slide wasallowed todry fori24 a to 48 hoursprotected fromrdust to -,.assure complete evaporation of solvent. Fungusspores, ob-

tained under controlled conditions, wereususa pended in distilled watercontaining a nutrient and added to the fungicide deposit on the slide. Apiece of platinum wire about three incheslong was sealed to a glass rodand a loop one mm. in diameterfor nedon the end. The loop wasusedtoitransfer the-spores to the fungicide deposit on'theslide; Sporeswerealways carefully transferred' tov the center :of the fungicidedeposit.

.aSlides so prepared, ;i.-e. containing fungicide deposit v-.with sporesdeposited thereon were .Dlfioedin a,--moisture chamber sealed withdistilled water.;;and incubated ,at -7 i2 F. for 24 hours angexaminedunder the low ,power (180K) of a microscopeforgermination.Duplicate; runs were made-infififihtdse tocheck the results.

After examining the slides ,under the micro- 55391 .301: rnos min on hadtak place about ten spores were transferred to an agar slant on apieceofagar about the size-of a=match head where-the fungicide removed :withthem could difillse away. When the chemical concentration ofai the-fungicide diminishes enough the spores havelthe necessary nutrients togerminate if they have .notbeenkilled already.

Each slant was incubated at 70i2 F'. for 24 hours. Usingsterile-techm'que the small piece ofiagar-waeremoved from the slant,placed on a clean slide and-examined under the microscope for sporegermination. I

Ilsing the procedure outlined above, a 0.1 per cent solution ofN,Nr-dimethyl-S-tert-butylthiosulfenyl-flithiocarbamate effected acomplete kill on; 5 clerotim'ja fructicola, Glomerella :cz'ngulabaandrAl rm lol c Example II :S1ideswere prepared by the procedure ofvvExamplel uSinga 0.1percentsolution of piperidine-Setertrhutylthiosulfenyl ,dithiocarbamate. Thiscompound,eifected-a-complete kill-on Sclerotinta ftucticola, Glomerellacingulam and Alternaria oleracea.

7 Example IH :Slides'wereprepared by the procedure of 'Example :I usinga0.1-per cent solution of N,N- diethyl-S-tert-butylthiosulfenyldithiocarbamate. This :compound prevented the germination ofAltemorimclemcec :andiGlomerella .c'mgu Zata.

' "Example IV g gueous, solution. containin .1 parts :per million of"N,N-dimethyl-S-tert=butylthiosulfenyl dith oce e e asp ep e us ngvthetesttube dilutiontechnique. To two cc. of thissolution in rachemically clean test.tube.vwas.added 0;5 o

a spore suspension, prepared by diluting a 500,000 per ml. sporesuspension with an equal volume of concentrated Czapeks solution,containing approximately 125,000 spores of Glomerellm cinafter to 24hours of incubation. "N,N-.dimethyl-S-tert-butylthiosulfenyldithiocarbamate in a concentration of 0.1 part per million prevented thegermination of Glomerella cingulata.

Example V Slides..were prepared by the procedure of Example *IV.Piperidine-S-tert-butylthiosulfenyl dithiocarba-1nateqii a concentrationof 0.3 parts ,erella cingulcata.

per million prevented the germination of Glom- Example VI Using the testtube dilution technique as described inExample IV, the'ED50 ofN,Nq-dimethyl-S-tertiary-butyl-thiosulfenyl, dithiocarbamate was foundto be 1.8 parts per-million against .S'clerotinia fructicola.

Example .VII

The following is anaccount of the infected barley test asameasure offungicidal activity:

A 9 cm. filter paper-is placed in'the bottom of a 10 cm. petri dish andvarying amounts of chemicals are added. If -possible-the chemical isdissolved in a solvent such as acetone, alcohol, benzene or water, butif it is insoluble in everything it is suspended either in acetone orwater. After the solution or suspension is applied to the paper, theliquid is allowed to'evaporate completely so the manner in which it isapplied does not enter into the-results. Ofcourse, the. water-solutionsneed not evaporate since .water is to be later anyway.

The amounts appliedto the -.papers-are5 mg. 1 mg. and 0.1 mg.which'corresponds to-0.1%, 0.02% and 0.002% if it would .all dissolve inthe 5 ml. of water applied tothepaper.

Ten grains of'barley infected with Helminthosporiumsativum are placed onthe treated papers with about 5 ml. of water and placedat 70 F. toincuat Tw r thre checksa s tup wit no chemical on the paper. Qbservationsare made after 3 and 6 days. In-,:t he checks-about of srainsof barleybecom .blac with the p rul s fungus and the blackm extends onto th papr- .Som routin of the barley-takes place, butthe il ngu interfereswiththe growth. On treatedpaper there is no; growth of fungus if thechemical is a good fungicide. The growth, of course, dependson-thezamount of fungicide present. With good fungicides growth of thefungus on the'seeds 13534150 prevented at a sufficient-concentration.

Results obtained using N,N-dimethyL-S-tertuty1thi su1i ny1dithiocarbamat and rvpiper dineeS-tert-butylthiosulfenyldithiocarbamate,

added the pomt'susuallyfaH-near-a straight li-n The EDoO is.thenextrapolated from-the line or curveras the dosage in part p m l oncessa to.. 1i 2i. .t ge mination and growth-ch50 per cent of the'fungup'oics.

according to the above-described procedure, are recorded below:

Growth ratio is a comparison of the growth of roots of treated seeds tothe growth of roots of fungus free seeds. Fungus free seeds are obtainedby treating infected seeds with a known fungicide which isnon-phytotoxic. Growth ratios not recorded on checks because the fungusoften destroys part or all the roots and provides an unreliable reading.

As the growth ratios indicate, these compounds are phytotoxic to theseeds as well as to the fungus at high concentrations. However, they arenontoxic to seeds at low concentrations at which they retain theirfungicidal activity.

Reasonable variation and modification are possible within the foregoingdisclosure and the appended claims to the invention the essence of whichis that thiosulfenyl dithiocarbamates, as indicated, have beendiscovered to possess fungicidal activity of considerable value.

We claim:

1. A fungicidal composition having as an essential active ingredient, ina concentration of 0.1 to 1090 parts per million in an inert solvent, athiosulfenyl dithiocarbamate selected from the group consisting ofN,N-dimethyl-S-tert-butylthiosulfenyl dithiocarbamate,piperidine-S-tertbutylthiosulfenyl dithiocarbamate andN,N-diethyl-S-tert-butylthiosulfenyl dithiocarbamate.

2. The composition of claim 1 wherein the solvent is ethanol.

3. The composition of claim 1 wherein the thiosulfenyl dithiocarbamateis N,N-dimethyl-S- thiosulfenyl dithiocarbamate is N,N-diethyl-S-tert-butylthiosulfenyl dithiocarbamate.

6. The method for preventing a plant disease due to a fungus growthwhich comprises applying to said plant a thiosulfenyl dithiocarbamateselected from the group consisting ofN,N-dimethyl-S-tert-butylthiosulfenyl dithiocarbamate,piperidine-S-tert-butylthiosulfenyl dithiocarbamate andN,N-diethyl-S-tertbutylthiosulfenyl dithiocarbamate.

7. The method of claim 6 wherein the thiosulfenyl dithiocarbamate isN,N-dimethyl-S-tertbutylthiosulfenyl dithiocarbamate.

8. The method of claim 6 wherein the thiosulfenyl dithiocarbamate ispiperidine-S-tert-butylthiosulfenyl dithiocarbamate.

9. The method of claim 6 wherein the thiosulfenyl dithiocarbamate isN,N-diethyl-S-tertbutylthiosulfenyl dithiocarbamate.

10. The method for preventing plant disease due to a fungus growth whensaid fungus is selected from a group consisting of Sclerotinz'afructicola, Glomerella cingulata and Alternaria olemcea which comprisesapplying to said plant a thiosulfenyl dithiocarbamate selected from thegroup consisting of N,N-dimethyl-S-tert-butylthiosulfenyldithiocarbamate, piperidine-S-tertbutylthiosulfenyl dithiocarbamate, andN,N-diethyl-S-tert-butylthiosulfenyl dithiocarbamate.

11. The method of claim 10 wherein the thiosulfenyl dithiocarbamate isN,N-dimethyl-S- tert-butylthiosulfenyl dithiocarbamate and the fungus isSclerotinza jructicola.

12. The method of claim 10 wherein the thiosulfenyl dithiocarbamate ispiperidine-S-tertbutylthiosulfenyl dithiocarbamate and the fungus isSclerotim'a fructicola.

13. The method of claim 10 wherein thethiosulfenyl dithiocarbamate isN,N-diethyl-S-tertbutylthiosulfenyl dithiocarbamate and the fungus isGlomerella cingulata.

LYLE D. GOODHUE. WINSTON M. FLORENCE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,972,961 Tisdale et a1 Sept. 11,1934 2,139,935 Claudin Dec. 13, 1938 2,325,720 Urbschat et a1. Aug. 3,1943 2,390,713 Hunt Dec. 11, 1945

1. A FUNGICIDAL COMPOSITION HAVING AS AN ESSENTIAL ACTIVE INGREDIENT, INA CONCENTRATION OF 0.1 TO 1000 PARTS PER MILLION IN AN INERT SOLVENT, ATHIOSULFENYL DITHIOCARBAMATE SELECTED FROM THE GROUP CONSISTING OFN,N-DIMETHYL-S-TERT-BUTYLTHIOSULFENYL DITHIOCARBAMATE,PIPERIDINE-S-TERTBUTYLTHIOSULFENYL DITHIOCARBAMATE ANDN,N-DIETHYL-S-TERT-BUTYLTHIOSULFENYL DITHIOCARBAMATE.